Proteins, enzymes, and hormones for use in human health care must be purified to homogeneity. These separation and purification steps represent a significant portion of the manufacturing cost for drugs and pharmaceuticals, yet very little fundamental scientific information is available for biological separation processes. Chromatography, including ion-exchange, affinity, and gel filtration, is common to many separation and purification schemes. Ion-exchange and affinity chromatography are commonly run with gradient changes in pH, ionic strength, and/or counter-ion concentration. In order to institute mathematical optimization and design, and thus to improve the economics of chromatographic processes, basic adsorption parameters as functions of these gradients are required. This biological adsorption data can be tested against well-known mechanisms for adsorptive separations of organic mixtures and wastewater streams, and conventional adsorption theory can then be expanded to accurately explain and predict biological separation phenomena at the molecular level. Experimental studies will be done on well-characterized proteins and enzymes such as human serum albumin and human placental alkaline phosphatase in order to identify the basic principles inherent in ion-exchange or affinity chromatography. These principles can then be applied to purification of other biomedically-important substances.